A method for treating vulcanized rubber, the method including the steps of (i) providing an aqueous stream that includes vulcanized rubber particles suspended in water, (ii) feeding the aqueous stream to the top of a hydraulic downdraft column, (iii) conducting the aqueous stream to the bottom of the hydraulic downdraft column, (iv) conducting the aqueous stream into an ultrasonic treatment zone, (v) subjecting the aqueous stream to ultrasonic energy and, (vi) conducting the aqueous stream up a hydraulic updraft column.